Added vertex-limited network flow reduction

[iiloni-umd]

Describe your change:

Implemented a reduction algorithm for flow networks that have capacities on vertices instead of edges. This reduction converts such a flow network into a standard flow network for which the Ford-Fulkerson algorithm can compute a max-flow.

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
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• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[algorithms-keeper]

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Repository:

• Contributing guidelines
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Python:

• Formatted string literals (f-strings)
• Type hints
• doctest
• unittest
• pytest

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[algorithms-keeper]

As there is no test file in this pull request nor any test function or class in the file networking_flow/vertex_limited.py, please provide doctest for the function vertex_limited

Please provide return type hint for the function: vertex_limited. If the function does not return a value, please provide the type hint as: def function() -> None:

Please provide type hint for the parameter: graph

Please provide type hint for the parameter: limits

[iiloni-umd]

It appears that ruff is catching issues from files that I have not modified. I'm not sure what I need to do to get ruff to pass.

[tianyizheng02]

It appears that ruff is catching issues from files that I have not modified. I'm not sure what I need to do to get ruff to pass.

Other people have been having that issue with their PRs too. Try running ruff --fix .

[iiloni-umd]

These are the results from running ruff --fix .

I did not contribute to the maths directory, is there something I can do to make this PR pass or would I need to modify those other files?

[tianyizheng02]

Not sure. It also seems that whether ruff identifies these errors is system-dependent: the errors appear when GitHub Actions runs ruff on my fork but not when I run ruff on my local git repo. @cclauss any ideas on how @iiloni-umd and others can get rid of these ruff errors?

[tianyizheng02]

@iiloni-umd The ruff issue has been fixed in #8732. Update your branch and ruff should pass this time

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[tianyizheng02]

@iiloni-umd Could you rebase your branch to bring in the latest commits? The ruff errors have been fixed

[tianyizheng02]

Closing due to lack of response. In addition, please read the contributing guidelines to make sure that your code follows our requirements